For Nevile Gwynne, a self-taught teacher whose book on grammar and slot on Radio 5’s Up All Night have earned him a cult following which includes Prince Charles, the answer is simple. As he explained to Elizabeth Grice inthis interview, he believes that good grammar underpins everything from our decision-making to our happiness.

These questions are intended to be in increasing order of difficulty. None of them is purely gimmicky. In every case effortless mastery of the principles involved will reflect one's ability to reason, understand and communicate.